I’m from Vietnam. I’ve been in the UK for 10 years now. When I met my English husband 13 years ago at 19 I knew 0 English. We communicated using machine translation. So that’s when I started learning English. Fast forward to present day after immersion, living in an English speaking country, formal study, etc. and I’d say my writing and listening (understanding) are good, but my speaking and reading are still bad. I kind of gave up on trying to become fluent at this point.
Thing is your ability to learn language drops with age. Children learn their first language at ridiculous rate, teenagers learn fast, 30y olds learn slowly, 50 years and above have problem to ever get fluent